“Citizenfour" won the Oscar for documentary feature on Sunday night and director Laura Poitras thanked NSA document leaker Edward Snowden for his "courage."

The film, an examination of personal privacy and security in the digital age, is also an up-close portrait of Snowden in the decisive moments when he captured the world’s attention by releasing information on classified U.S. government surveillance programs.

"The disclosures that Edward Snowden revealed don't only expose a threat to our privacy but to our democracy itself," Poitras said in accepting the award. "When the most important decisions being made affecting all of us are made in secret, we lose our ability to check the powers that control."

She added, "Thank you to Edward Snowden for his courage and for the many other whistle-blowers."

The award went to Poitras and producers Mathilde Bonnefoy and Dirk Wilutzky, who all took to the stage on Sunday night along with journalist Glenn Greenwald and Snowden's girlfriend Lindsay Mills.

Click through to see the top winners and nominees of the 87th Academy Awards.

Shortly after the announcement of the award, the American Civil Liberties Union released a statement from Snowden that read, “When Laura Poitras asked me if she could film our encounters, I was extremely reluctant. I’m grateful that I allowed her to persuade me. The result is a brave and brilliant film that deserves the honor and recognition it has received. My hope is that this award will encourage more people to see the film and be inspired by its message that ordinary citizens, working together, can change the world.”

A large portion of the film takes place in a Hong Kong hotel room alongside Snowden as a series of news articles began to be released stemming from secret documents he gained access to while working as a contractor for the U.S. intelligence community. A startling primary historical document, Poitras has compared the experience to being in the parking garage with Watergate whistle-blower Deep Throat.

The Oscar completes a whirlwind run for the movie following its premiere in October at the New York Film Festival. Launched as something of a torpedo into the season -- made under a veil of secrecy, few knew of the film’s existence until just before its premiere -- it has since won honors from the Directors Guild of America, International Documentary Assn., Cinema Eye, Gotham Awards, Spirit Awards and numerous critics groups. “Citizenfour” will have its broadcast premiere Monday on HBO.

Poitras was previously nominated for the Oscar for her 2006 documentary on the Iraq war, “My Country, My Country.”

Also nominated was Rory Kennedy’s “Last Days in Vietnam.” The film, true to its title, is a look at the final days of the United States in Vietnam in April 1975, leading to the dramatic final airlift.

Orlando von Einsiedel’s “Virunga” is an examination of the efforts of a group of workers in the Virunga National Park in the Democratic Republic of Congo as they fight to save the dwindling numbers of mountain gorillas against poachers, civil war and corporations searching for oil. As with last year’s nominee “The Square,” the film received an unusually high-profile advertising campaign thanks to distributor Netflix.

“The Salt of the Earth,” is a portrait of the Brazilian photographer Sebastiao Salgado directed by Wim Wenders and the subject’s son, Juliano Ribeiro Salgado. Though he is still most widely known as a director of fiction films such as “Paris, Texas” and “Wings of Desire,” co-director Wenders is now a three-time nominee for his documentary work, previously recognized for “Pina” and “Buena Vista Social Club.”

Another film about a photographer, John Maloof and Charlie Siskel’s “Finding Vivian Maier,” is an investigation of a previously unknown artist. Maier, who died in 2009 at age 83, had lived her life working as a nanny in New York and Chicago. Upon her death, thousands upon thousands of photographs she took, many of everyday street scenes, were discovered. Never exhibited in her lifetime, they were embraced and her work widely hailed.